Disentangling the effect of adult biomass and temperature on the recruitment dynamics of fishes

Here we analyzed the relation between recruitment dynamic (recruitment or recruitment success) and temperature of 57 commercial fish stocks of the North Atlantic. We showed that, although the effect of temperature was generally significant, spawning biomass is the main factor governing recruitment dynamic. A significant effect of spawning biomass was evident for 67% of all stocks analyzed in this study. For gadoids, the effect of spawning biomass was larger than the effect of temperature (both in terms of number of stocks and proportion of variance explained). For clupeids, spawning biomass was more important than temperature for a higher number of stocks, but the strength of the two effects, when present, was similar. Also, stocks living in colder and warmer areas showed, respectively, a positive and negative response to temperature for both families. Our results highlight that failing to account for spawning biomass effect in climate-recruitment studies could mask the influence of climate variability on recruitment dynamic. In this context, although management of several exploited fish populations cannot be entirely decoupled from the effect of climate on stock reproductive success, it is likely that the observed changes in exploited fish population dynamics are mainly the consequences of an unsustainable human impact and not climate changes.